A question for you archeology metallurgical, *and now forensic* experts out there...

I am running an adventure in a home-brewed world, which is a desert, wherein the PC's go to an ancient tower in a particularly barren spot. There is no humidity or any life to speak of, where the tower is. It is built on top of a gigantic slab of rock, and there is no sand in the area. The tower itself has several open doors and windows, so the wind can get in (though there is no sand or loose debris to scour items). If the occupants of the tower died 700 years ago and it has not seen life since, what would be the conditions of the items within? What would be the effects of time and environment on the following:
Steel
Iron
Bronze
Silver
Gold
Wood
Leather (treated)